U.S. patent application number 09/738397 was filed with the patent office on 2002-08-22 for disposable products having materials having shape-memory.
Invention is credited to Garvey, Michael J., Odorzynski, Thomas Walter, Soerens, Dave Allen, Topolkaraev, Vasily A., Uitenbroek, Duane Girard.
Application Number | 20020115977 09/738397 |
Document ID | / |
Family ID | 24967826 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020115977 |
Kind Code |
A1 |
Topolkaraev, Vasily A. ; et
al. |
August 22, 2002 |
Disposable products having materials having shape-memory
Abstract
The present invention relates to shape deformable materials,
which are capable of (1) being deformed, (2) storing an amount of
shape deformation, and (3) recovering at least a portion of the
shape deformation when exposed to electromagnetic radiation (EMR)
energy. The shape deformable materials can advantageously be in the
form of films, fibers, filaments, strands, nonwovens, and
pre-molded elements. The shape deformable materials of the present
invention may be used to form products, which are both disposable
and reusable. More specifically, the shape deformable materials of
the present invention may be used to produce products such as
disposable diapers, training pants, incontinence products, and
feminine care products.
Inventors: |
Topolkaraev, Vasily A.;
(Appleton, WI) ; Odorzynski, Thomas Walter; (Green
Bay, WI) ; Soerens, Dave Allen; (Neenah, WI) ;
Garvey, Michael J.; (Appleton, WI) ; Uitenbroek,
Duane Girard; (Little Chute, WI) |
Correspondence
Address: |
JOHN S. PRATT
KILPATRICK STOCKTON LLP (KIMBERLY CLARK)
1100 PEACHTREE STREET
SUITE 2800
ATLANTA
GA
30309
US
|
Family ID: |
24967826 |
Appl. No.: |
09/738397 |
Filed: |
December 15, 2000 |
Current U.S.
Class: |
604/385.24 ;
156/272.2; 156/272.4; 156/275.1; 604/367; 604/370 |
Current CPC
Class: |
A61F 13/47263 20130101;
A61F 13/4902 20130101; B29L 2031/4878 20130101; A61F 13/15203
20130101; B29C 35/0805 20130101; B29C 61/00 20130101 |
Class at
Publication: |
604/385.24 ;
604/367; 604/370; 156/272.2; 156/272.4; 156/275.1 |
International
Class: |
A61F 013/15; A61F
013/20; B32B 031/00 |
Claims
What is claimed is:
1. A disposable article comprising an EMR responsive material
attached to one or more additional layers; wherein the EMR
responsive material comprises: at least one shape deformable matrix
material; wherein the EMR responsive material is capable of being
deformed in at least one spatial dimension when exposed to one or
more external forces, is capable of maintaining a degree of
deformation in at least one spatial dimension once the external
force is removed, and is capable of exhibiting a change, or percent
recovery, in at least one spatial dimension when subjected to an
activation energy in the form of electromagnetic radiation for less
than about one second.
2. The disposable article of claim 1, wherein the shape deformable
matrix material is selected from a segmented block copolymers
comprising one or more hard segments and one or more soft segments;
polyester-based thermoplastic polyurethanes; polyether-based
polyurethanes; polyethylene oxide; polybutylene succinate;
polybutylene succinate-adipate; polyhydroxybutyrate-co-valerate;
polycaprolactone; poly(ether ester) block copolymers; sulfonated
polyethylene terephthalates; poly(vinylidene chloride); vinylidene
chloride-containing copolymers; polylactides; polyamides;
poly(amide esters); poly(ether amide) copolymers; or mixtures
thereof.
3. The disposable article of claim 2, wherein the shape deformable
matrix material comprises a segmented block copolymer comprising
one or more hard segments and one or more soft segments, where
either the soft segment, the hard segment, or both contain
functional groups or receptor sites that are responsive to EMR.
4. The disposable article of claim 3, wherein the functional groups
are selected from urea, sulfone, amide, nitro, nitrile, isocyanate,
ketone, ester, aldehyde, phenol, carboxyl, vinylidene chloride,
ethylene oxide, methylene oxide, epoxy, and amine groups; ionic
groups, such as sodium, zinc, or potassium; or receptor sites
having an unbalanced charge distribution formed from one or more of
the above groups.
5. The disposable article of claim 2, wherein the shape deformable
matrix material comprises a segmented block copolymer comprising an
elastomer.
6. The disposable article of claim 5, wherein the elastomer is
selected from polyurethane elastomers, polyether elastomers,
poly(ether amide) elastomers, polyether polyester elastomers,
polyamide-based elastomers, or mixtures of these polymers.
7. The disposable article of claim 6, wherein the elastomer is
selected from polyurethane elastomers or poly(ether amide)
elastomers.
8. The disposable article of claim 1, further comprising an
electromagnetic absorber.
9. The disposable article of claim 8, wherein the electromagnetic
absorber is selected from silicon oxide, aluminum oxide, aluminum
hydroxide, carbon black, zinc oxide, barium titanate, polyanilines,
polypyrroles, polyalkythiophenes, chiral polymers, or mixtures
thereof.
10. The disposable article of claim 8, further comprising a
non-activatable additional material selected from non-elastomeric
polymers, tackifiers, anti-blocking agents, fillers, antioxidants,
UV stabilizers, polyolefin-based polymers, ormixtures thereof.
11. The disposable article of claim 10, wherein the EMR responsive
material comprises from about 40 to about 99.5 weight percent of
shape deformable polymer/EMR absorbers and from about 60 to about
0.5 weight percent of additional non-activatable materials.
12. The disposable article of claim 11, wherein the EMR responsive
material comprises from about 60 to about 99.5 weight percent of
shape deformable polymer/EMR absorbers and from about 40 to about
0.5 weight percent of additional materials.
13. The disposable article of claim 12, wherein the EMR responsive
material comprises from about 80 to about 99.5 weight percent of
shape deformable polymer/EMR absorbers and from about 20 to about
0.5 weight percent of additional non-activatable materials.
14. The disposable article of claim 1, wherein the EMR responsive
material has a dielectric loss factor measured in the EMR frequency
range of about 10 MHz to about 30 GHz of not less than about
0.05.
15. The disposable article of claim 14, wherein the EMR responsive
material has a dielectric loss factor measured in the EMR frequency
range of about 10 MHz to about 30 GHz of not less than about
0.1.
16. The disposable article of claim 15, wherein the EMR responsive
material has a dielectric loss factor measured in the EMR frequency
range of about 10 MHz to about 30 GHz of not less than about
0.20.
17. The disposable article of claim 16, wherein the EMR responsive
material has a dielectric loss factor measured in the EMR frequency
range of about 10 MHz to about 30 GHz of not less than about
0.25.
18. The disposable article of claim 1, wherein the one or more
additional layers are selected from films, nonwoven webs, woven
fabrics, foams, or a combination thereof.
19. The disposable article of claim 1, wherein the disposable
article is selected from diapers, training pants, adult
incontinence products, feminine care products, sanitary napkins
tampons, health care products, wound dressings, surgical drapes, or
surgical gowns.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method of causing the
shape deformation of a material by subjecting the material to
electromagnetic radiation.
BACKGROUND OF THE INVENTION
[0002] Elastomeric materials have been long and extensively used in
garments, both disposable and reusable products. These elastomeric
materials may be attached to the disposable product by several
methods. At one time, elastic was applied to the substrate by
sewing. (See U.S. Pat. No. 3,616,770 to Blyther et al.; and U.S.
Pat. No. 2,509,674 and RE 22,038 to Cohen). A newer method for
attaching elastomeric material to a substrate is by use of an
adhesive. (See U.S. Pat. No. 3,860,003 to Buell.) Welding, such as
sonic welding, has also been used to attach elastomeric material to
a disposable product. (U.S. Pat. No. 3,560,292 to Butter).
Laminates having an elastomeric layer and a co-extensive skin layer
have also been used. (U.S. Pat. No. 5,429,856 to Kruger et
al.).
[0003] These methods of attachment present several problems. First
is the problem of how to keep the elastic in a stretched condition
while applying the elastic to the substrate. Another problem is
that attachment of a ribbon of elastomeric material will
concentrate the elastomeric force in a relatively narrow line. This
may cause the elastic to pinch and irritate the wearer's skin. (See
U.S. Pat. Nos. 3,860,003; 4,352,355; and 4,324,245 to Musek et al.;
U.S. Pat. No. 4,239,578 to Gore; and U.S. Pat. Nos. 4,309,236 and
4,261,782 to Teed.) Other disadvantages of conventional attachment
methods include speed, ease of manufacture, and cost. More
importantly, difficulties may be encountered in maintaining a
uniform tension on the elastic layer during its attachment to the
substrate and also in handling the shirred article once the elastic
layer is relaxed.
[0004] Heat-responsive elastomeric films overcome some of these
detriments. Heat-responsive elastomers exist in two forms: a
thermally-stable and a thermally-unstable form. The
thermally-unstable form is created by stretching the material while
heating near its crystalline or second phase transition
temperature, followed by a rapid quenching to freeze in the
thermally-unstable, extended form. The elastomeric film can then be
applied to a disposable product, for example a diaper, and heated
to shirr or gather the elastomeric material, thereby producing a
thermally-stable form of the elastomeric material. Examples of
heat-responsive elastomeric films are disclosed in U.S. Pat. No.
4,681,580 to Reising et al., U.S. Pat. No. 4,710,189 to Lash, U.S.
Pat. No. 3,819,401 to Massengale et al., U.S. Pat. No. 3,912,565 to
Koch et al., and U.S. Pat. No. RE 28,688 to Cook.
[0005] These polymers have several disadvantages. The first of
these disadvantages involves the temperature to which the
elastomeric material must be heated to stretch the material to its
thermally-unstable form. This temperature is an inherent property
of the elastomeric material. Therefore, the disposable product is
often difficult to engineer because temperatures useful for the
production of the overall product may not be compatible with the
temperature necessary to release the thermally-unstable form of the
elastomer. Frequently, this temperature is rather high and can be
detrimental to the adhesive material used to attach the various
product layers. Another drawback to the use of heat-responsive
elastomers is that they can constrain the manufacturing process,
rendering it inflexible to lot variations, market availability,
cost of raw materials, and customer demands.
[0006] U.S. Pat. No. 4,820,590 to Hodgkin et al. describes an
elastomeric blend of three components to reduce the temperature
required for the material to resume its heat stable form.
Additionally, GB Patent 2,160,473 to Matray et al. proposes an
elastomer which will shrink at an elevated temperature, for example
at or above 170.degree. F. The advantageous features of these
materials, compared to the heat-shrinkable materials discussed
above, is that it does not require preheating during the stretching
operation, but rather can be stretched at ambient temperatures by a
differential speed roll process or by "cold rolling." Problems with
use of these elastomers include difficulties inherent in applying a
stretched elastic member to a flexible substrate such as a
disposable diaper. Although some of the elastomers proposed have
the advantage that they can be applied at ambient conditions in a
highly stretched, unstable form, subsequent, often extreme, heating
is required to release the thermally-unstable form to a contracted
thermally-stable form. The temperature of this heat release is
generally inflexible since it is determined at the molecular level
of the elastomer. Thus, selection of materials for the disposable
product which are compatible with this heating step is
required.
[0007] Further, when individual heat activated elastic materials
are used, the heat activation is generally accomplished by passing
the garments through a heated air duct for a period of time. Since
thermal heating must be transferred from an outer surface of the
garment to inner portions of the garment, distribution of the
activation means (i.e., thermal heat) throughout the garment takes
considerable amounts of time and energy, resulting in an
inefficient activation process. In such a configuration, the
activation process typically takes several seconds, or even
minutes, to elevate the temperature of the elastic material to a
level at which activation takes place, causing the elastic material
to retract and gather the garment. As a result, such heating
processes can consume vast amounts of energy and undesirably result
in slower manufacturing speeds.
[0008] What is needed in the art is a method of activating a shape
deformation of a material within 1 second and without using an
inefficient thermal heating activation process. What is also needed
in the art is a method of activating a shape deformation of a
material without substantially increasing the temperature of the
material.
SUMMARY OF THE INVENTION
[0009] The present invention addresses some of the difficulties and
problems discussed above by the discovery of materials capable of
exhibiting a shape deformation when exposed to electromagnetic
radiation. These materials exhibit a change in at least one spatial
dimension when subjected to an activation energy for less than one
second. The materials of the present invention find applicability
in a number of products, including products containing a gatherable
or elastic part.
[0010] The present invention is further directed to a method of
causing the shape deformation of materials having a desired amount
of locked-in shape deformation. The method comprises subjecting the
material to an activation energy for an amount of time, typically
less than about one second. The method may be used to cause the
shape deformation of the above-described material itself or a
product containing the above-described material.
[0011] In addition, the present invention is directed to articles
of manufacture, which contain the above-described materials having
a desired amount of locked-in shape deformation. Suitable products
include, but are not limited to, products containing an elastic
portion, such as diapers, as well as, products having a shrinkable
or expandable component. The present invention is also directed to
a method of making various articles of manufacture, which contain
the above-described materials having a desired amount of locked-in
shape deformation, and are subsequently subjected to
electromagnetic energy.
[0012] The present invention is also directed to a method of
building shape deformable polymers in an effort to optimize the
interaction of the shape deformable polymer with a selected
activation energy. By adjusting the chemical structure of the shape
deformable polymer, one can tailor a specific shape deformable
polymer in such a way as to maximize the interaction of the shape
deformable polymer with a selected activation energy, such as
electromagnetic energy (EMR) having a specific wavelength.
[0013] These and other features and advantages of the present
invention will become apparent after a review of the following
detailed description of the disclosed embodiments and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention is further described by the
accompanying drawings, in which:
[0015] FIG. 1 representatively shows a perspective view of a method
according to one embodiment of the present invention;
[0016] FIG. 2 representatively shows a top plan view of a composite
material according to one embodiment of the present invention;
[0017] FIG. 3 representatively shows a partially cut away, top plan
view of an absorbent article according to one embodiment of the
present invention; and
[0018] FIG. 4 graphically shows the optimum percent recovery range
for a specific shape deformation material and its relationship to
the combined effects of power of an industrial microwave generator
and the speed of the shape deformation material through the
industrial microwave generator.
[0019] FIG. 5 graphically displays the change in value of the
dielectric loss factor of polyether amide versus frequency at
selected temperatures.
[0020] FIG. 6 graphically displays the change in value of the
dielectric loss factor of polyurethane versus frequency at selected
temperatures.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention addresses some of the difficulties and
problems discussed above by the discovery of materials, which are
capable of exhibiting a shape deformation when exposed to
electromagnetic radiation (EMR), and methods of using the same.
These materials exhibit a change in at least one spatial dimension
when subjected to an activation energy for less than about one
second. Unlike known materials and methods, the materials and
methods of the present invention maximize the amount of "locked-in"
shape deformation within the material, as well as, maximize the
percent change in one or more spatial dimensions of the material.
Further, unlike previous recovery methods which involve a heating
step, the present invention is directed to a method of causing a
change in one or more spatial dimensions of the material without a
substantial change in the temperature of the material. The recovery
method of the present invention instead comprises subjecting the
material to an amount of electromagnetic radiation sufficient to
cause a desired change in one or more spatial dimensions without a
substantial change in the temperature of the material. The
materials and methods of the present invention find applicability
in a number of products and processes.
[0022] One method of measuring the change in one or more spatial
dimensions of a material is given by the equation below: 1 % R = (
i - f ) i .times. 100
[0023] wherein:
[0024] %R represents the percent change, or the percent recovery,
of one spatial dimension of the material;
[0025] .delta..sub.i represents the dimension prior to subjection
to an activation energy; and
[0026] .delta..sub.f represents the dimension after subjection to
the activation energy.
[0027] The above equation may be used to determine the percent
recovery of one or more spatial dimensions of the shape deformable
material of the present invention. Further, the above equation may
be used on any material capable of experiencing a change in a
spatial dimension. Suitable materials having a shape deformation
and a desired percent recovery are given below.
[0028] Shape Deformable Material Components
[0029] The present invention is directed to shape deformable
materials, which exhibit a change in at least one spatial dimension
when subjected to an activation energy of electromagnetic radiation
for less than about one second. Suitable materials include any
material or blend of materials, which has the following properties:
(1) is capable of being deformed in at least one spatial dimension
when exposed to one or more external forces, (2) is capable of
maintaining a degree of deformation in at least one spatial
dimension once the external force is removed, and (3) is capable of
exhibiting a change, or percent recovery, in at least one spatial
dimension when subjected to an activation energy in the form of
electromagnetic radiation for less than about one second. The shape
deformable materials of the present invention may contain one or
more of the following classes of components:
[0030] Shape Deformable Matrix Materials
[0031] The shape deformable materials of the present invention
contain at least one shape deformable matrix material. As used
herein, the term "shape deformable matrix material" is used to
describe a material having the three above-mentioned properties,
and is also capable of encompassing one or more filler materials.
Suitable shape deformable matrix materials include, but are not
limited to, polymers and ionomer resins. Examples of ionomer resins
useful in the present invention include, but are not limited to,
polyurethane ionomer resins and segmented block copolymer ionomer
resins. Other ionomer resins, e.g. ionomer resins known under the
trade name SURLYN.RTM. (available from DuPont) may also be used.
Preferably, the ionomer resins used have a high ion content.
[0032] In one embodiment of the present invention, the shape
deformable matrix material comprises at least one polymer having
the above-mentioned properties. Suitable polymers include, but are
not limited to, segmented block copolymers comprising one or more
hard segments and one or more soft segments; polyester-based
thermoplastic polyurethanes; polyether-based polyurethanes;
polyethylene oxide; polybutylene succinate; polybutylene
succinate-adipate; polyhydroxybutyrate-co-valerat- e;
polycaprolactone; poly(ether ester) block copolymers; sulfonated
polyethylene terephthalates; poly(vinylidene chloride); vinylidene
chloride-containing copolymers; polylactides; polyamides;
poly(amide esters); poly(ether amide) copolymers; and mixtures
thereof. Desirably, the shape deformable matrix material comprises
a segmented block copolymer comprising one or more hard segments
and one or more soft segments, where either the soft segment, the
hard segment, or both contain functional groups or receptor sites
that are responsive to electromagnetic radiation (EMR).
[0033] As used herein, the phrase "responsive to electromagnetic
radiation (EMR)" is used to describe functional groups and/or
receptor sites within a polymer, which, when exposed to
electromagnetic radiation, convert the electromagnetic radiation
into molecular rotational energy, which enables a desired amount of
shape recovery of a shape deformed polymer. Suitable functional
groups and/or receptor sites include, but are not limited to,
functional groups such as urea, sulfone, amide, nitro, nitrile,
isocyanate, ketone, ester, aldehyde, phenol, carboxyl, vinylidene
chloride, ethylene oxide, methylene oxide, epoxy, and amine groups;
ionic groups, such as sodium, zinc, and potassium; and receptor
sites having an unbalanced charge distribution formed from one or
more of the above groups. Desirably, the functional groups comprise
one or more functional groups having a high dipole moment (i.e.,
greater than about 1.5 Debye) such as urea, sulfone, amide, nitro,
nitrile, isocyanate, and ketone groups.
[0034] More desirably, the segmented block copolymer is an
elastomer. Suitable shape deformable elastomers for use in the
present invention include, but are not limited to, polyurethane
elastomers, polyether elastomers, poly(ether amide) elastomers,
polyether polyester elastomers, polyamide-based elastomers, and
mixtures of these polymers. Some non-elastomeric polymers may be
used. These polymers can provide some degree of recovery when
exposed to activation energy such as heat or EMR. Examples of
non-elastomeric polymers useful in the present invention include,
but are not limited to, polybutylene succinate, polybutylene
succinate-adipate copolyesters, polyethylene oxide, polymers of
polylactic acid, blends and mixtures thereof.
[0035] In one embodiment of the present invention, the shape
deformable matrix material comprises a polyurethane. Suitable
polyurethanes for use in the present invention include, but are not
limited to, polyester-based aromatic polyurethanes, polyester-based
aliphatic polyurethanes, polyether-based aliphatic and aromatic
polyurethanes, polyurea, and blends and mixtures of these
polyurethanes. Such polyurethanes may be obtained, for example,
from Morton International (Chicago, Ill.). Examples of specific
polyurethanes, which can be used in the present invention include,
but are not limited to, MORTHANE.RTM. PS 370-200, MORTHANE.RTM. PS
79-200, MORTHANE.RTM. PN3429, and MORTHANE.RTM. PE 90-100.
[0036] In a further embodiment of the present invention, the shape
deformable matrix material includes a poly(ether amide) elastomer.
Poly(ether amide) elastomers, which may be used in the present
invention, may be obtained, for example, from Elf Atochem North
America, Inc. (Philadelphia, Pa.). Examples of such poly(ether
amide) elastomers include, but are not limited to, PEBAX.RTM. 2533,
PEBAX.RTM. 3533, and PEBAX.RTM. 4033.
[0037] Polyurethane elastomers and poly(ether amide) elastomers are
particularly useful as the shape deformable matrix material in the
present invention because they structurally consist of soft and
hard segments, which contain groups having high dipole moments
(i.e., isocyanate, amide, and ester groups), which, as discussed
above, are highly receptive to electromagnetic radiation. The hard
segments in these elastomers typically act as physical
cross-linking points for the soft segments, enabling an elastomeric
performance. Both hard and soft segments may contribute to the
shape deformation during a number of pre-activation treatments
described below, such as stretching, which provides "locked-in"
shape deformation, which may be recoverable by exposure to an
amount of activation energy in the form of EMR for less than about
one second.
[0038] In still another embodiment of the present invention, the
shape deformable matrix material includes a blend of an elastomeric
polymer and a non-elastomeric polymer. These blends may either be
co-extruded together, or may be formed into multi- or micro-layer
structures. These blends are advantageous since blending or
multi-layering/micro-layering of a shape deformation elastomer with
another non-elastomeric shape deformation polymer can improve
latent deformation properties, especially at lower stretching
temperatures, and can significantly increase recoverable
deformation as a result of activation by thermal energy or EMR
energy.
[0039] EMR Absorbers
[0040] Desirably, the shape deformable material of the present
invention further comprises one or more electromagnetic radiation
(EMR) absorbers. As used herein, the term "EMR absorber" is used to
describe additives, which further enhance the conversion of EMR
energy into molecular rotational energy of the shape deformable
material, which results in enhanced relaxation of the molecular
structure of the shape deformable matrix material (i.e., ability to
recovery from a latent, locked-in state). Examples of suitable EMR
absorbers for use in the shape deformable materials of the present
invention include, but are not limited to, silicon oxide, aluminum
oxide, aluminum hydroxide, carbon black, zinc oxide, barium
titanate, and mixtures of these. Other suitable EMR absorbers
include organic polymeric absorbers such as electrically conductive
polymers, e.g., polyanilines, polypyrroles and polyalkythiophenes,
and chiral polymers. EMR absorption of electrically conductive
polymers may be improved through doping. Chiral compounds useful as
EMR absorbers are characterized as being optically active, which
means they can rotate the plain optical polarization in certain
isotropic media, and they are not superimposable on its mirror
image.
[0041] EMR absorbers may be present within the shape deformable
matrix material or may be on one or more surfaces of the shape
deformable matrix material. Further, the EMR absorbers may be
uniformly distributed within the shape deformable matrix material
or may be non-uniformly distributed within the shape deformable
matrix material. In the latter case, a shape deformable material
may be produced, which exhibits non-uniform recovery of a latent,
locked-in deformation when exposed to an activation energy.
[0042] It should be noted that one or more of the above-mentioned
EMR absorbers may be used in combination with one or more shape
deformable matrix materials to prepare the shape deformation
materials of the present invention. Further, it should be noted
that one or more of the above-mentioned shape deformable polymers,
alone or in combination with one or more of the above-mentioned EMR
absorbers, may be used in combination with one or more
non-activatable materials to form a blend of shape deformable
material.
[0043] Non-Activatable Materials
[0044] As used herein, the term "non-activatable materials" is used
to describe any material, which lacks one or more of the three
properties mentioned above when describing suitable shape
deformable materials. Suitable non-activatable additional materials
include, but are not limited to, non-elastomeric polymers,
tackifiers, anti-blocking agents, fillers, antioxidants, UV
stabilizers, polyolefin-based polymers and other cost-saving
additives that may be added or blended to add beneficial
properties.
[0045] The amount of non-activatable material blended with the
above-mentioned shape deformable polymers and EMR absorbers may
vary as long as the resulting blend possesses a desired amount of
shape deformation properties. The blend may contain from about 40
to 99.5 weight percent of shape deformable polymer/EMR absorbers
and from about 60 to 0.5 weight percent of additional
non-activatable materials. Desirably, the blend contains from about
60 to 99.5 weight percent of shape deformable polymer/EMR absorbers
and from about 40 to 0.5 weight percent of additional materials.
More desirably, the blend contains from about 80 to 99.5 weight
percent of shape deformable polymer/EMR absorbers and from about 20
to 0.5 weight percent of additional non-activatable materials.
[0046] Configuration of Shape Deformable Materials
[0047] The shape deformation materials of the present invention may
possess a variety of shapes and sizes. The shape deformation
materials of the present invention may be in the form of films,
multi-layered or micro-layered films, laminates, filaments,
fabrics, foams, or any other three-dimensional form. The shape
deformation material may be formed by any method known to those of
ordinary skill in the art including, but not limited to, extrusion,
spray coating, foaming, etc. There is no limitation on the size of
the shape deformation material; however, the amount of shape
deformation and the percent recovery of the shape deformation
material may be limited if the size of the material is too
great.
[0048] In an alternative embodiment, materials that include a blend
of two shape-deformable polymers or a multi- or micro-layer
structure having two shape-deformable polymers demonstrate that
blending or multi-layering/micro-layering of a shape deformation
elastomer with another non-elastomeric shape deformation polymer
can improve latent deformation properties, especially at lower
stretching temperatures, and can significantly increase recoverable
deformation as a result of activation by thermal energy or EMR
energy.
[0049] Regardless of the size and shape of the shape deformation
material, the shape deformation material of the present invention
exhibits a change in at least one spatial dimension when subjected
to an activation energy for less than about one second. Typically,
the shape deformation material of the present invention exhibits a
change in one, two, or three dimensions. For example, when the
shape deformation material is in the form of a fiber, the shape
deformation material exhibits a change in the fiber length and/or
fiber diameter. When the shape deformation material is in the form
of a film, the shape deformation material exhibits a change in the
film length and/or film width and film thickness. A percent
recovery may be measured for each of the dimensions of the shape
deformation material.
[0050] As can be seen by the above equation, in order to maximize
the percent recovery of a given dimension, %R, the difference
between the dimension prior to (.delta..sub.i) and after subjection
to an activation energy (.delta..sub.f) needs to be maximized. The
present invention provides a method of maximizing the percent
recovery, %R, of a given dimension of a material. One factor, which
effects the ability to maximize the present recovery of a given
dimension, is the ability to "lock-in" a desired amount of shape
deformation in the material prior to subjecting the material to an
activation energy.
[0051] Preparation of Materials Having a Degree of Shape
Deformation
[0052] One aspect of the present invention is directed to a method
of preparing materials having a desired amount of "locked-in" shape
deformation. As used herein, the term "locked-in shape deformation"
refers to a recoverable amount of shape deformation in one or more
spacial dimensions of a given material, resulting from one or more
forces exerted on the given material. Suitable forces include, but
are not limited to, stretching, heating, cooling, compressing, etc.
The amount of locked-in shape deformation may vary depending upon a
number of factors including, but not limited to, the material
composition, the material temperature, the material treatment
procedures (i.e., the amount of stress administered to the
material), and any post-treatment procedures (i.e., quenching,
tension, etc.). A number of factors, which may contribute to the
locked-in shape deformation of a given material are discussed
below.
[0053] Stretching or Compressing
[0054] Stretching and compressing are ways to impart a locked-in
shape deformation to a shape deformation material of the present
invention. The amount of deformation resulting from stretching or
compressing is dependent upon a number of variables. Important
variables associated with stretching or compressing of a given
material include, but are not limited to, the stretch or draw
ratio, the stretching or compressing temperature, the stretching or
compressing rate, and post-stretching or post-compressing
operations, if any, such as heat setting or annealing
operations.
[0055] Additionally, other types of deformation may be used besides
stretching and compressing including, but not limited to, bending,
twisting, shearing, or otherwise shaping the material using complex
deformations.
[0056] Stretch or Draw Ratio
[0057] The amount of locked-in shape deformation that can be
imparted to a given material depends upon the stretch or draw
ratio. In general, the amount of locked-in shape deformation of a
material is typically larger when the draw ratio is larger.
Stretching of the material may be accomplished in one or more
directions, such as uniaxial or biaxial stretching. Stretching in
more than one direction, such as biaxial stretching, may be
accomplished simultaneously or sequentially. For example, when
sequential biaxial stretching a film of shape deformation material,
the first or initial stretching can be conducted in either the
machine direction (MD) or the transverse direction (TD) of the film
material.
[0058] In one embodiment of the present invention, the treated
material desirably possesses a draw or stretch ratio of at least
1.5 in one or more directions. More desirably, the treated material
possesses a draw or stretch ratio in one or more directions of from
about 2 to about 10. Even more desirably, the treated material
possesses a draw or stretch ratio in one or more directions of from
about 3 to about 7. Lower draw ratios may result in low shape
deformation and low recoverable deformation. However, low draw
ratios may be applicable to some embodiments of the present
invention, depending on specific applications and the desired
amount of shape deformation. Very high draw ratios during the
process of imparting shape-deformation memory may result in a
partial loss of shape memory as a result of unrecoverable plastic
deformations in the material.
[0059] Stretching Temperature
[0060] During stretching, the material sample may be optionally
heated. Desirably, stretching is conducted at temperatures below
the melting temperature of the material. In one embodiment of the
present invention wherein the material is a polymeric material, the
drawing temperature is not more than about 120.degree. C. and,
desirably, not more than about 90.degree. C. When the drawing
temperature is too high, the material can melt, become excessively
tacky, and/or become difficult to handle. In addition, excessively
high stretching temperatures can cause irreversible deformations in
which the shape deformation of the material is lost and the
original shape is not recoverable.
[0061] Stretching a given material at low temperatures may result
in a lower amount of locked-in shape deformation and low percent
recovery during activation. Generally, when the shape deformation
material comprises segmented block thermoplastic elastomers, it is
desired to stretch the material near the softening or glass
transition temperature of the hard segments. In some cases, when
the soft segments experience strain induced crystallization during
stretching, drawing the material near the crystalline transition
temperature of the soft segments is desired. This is the case, for
example, when the shape deformation material is a PEBAX.RTM.
elastomer.
[0062] Stretch Rate
[0063] The rate at which stretching is performed may also affect
the amount of locked-in shape deformation imparted to a given shape
deformation material. Suitable stretching rates will vary depending
upon the material to be stretched. As a general rule, stretching
may be accomplished at rates of at least about 50%/min. and as much
as about 5000%/min. Desirably, the stretching rate is from about
100%/min. to about 2500%/min. Higher stretching rates may be more
beneficial for process efficiency; however, very high stretching
rates may result in a material failure at reduced draw ratios. The
effect of stretching rate on locked-in shape deformation is
dependent upon the structure and composition of the material. For
some embodiments of the present invention, such as when the shape
deformation material comprises a thermoplastic polyurethane, the
stretching rate does not have a significant impact on the resulting
amount of locked-in shape deformation.
[0064] Post-Stretching Operations
[0065] The locked-in shape deformation properties of a shape
deformation material of the present invention may be affected by
post-stretching operations. A number of factors should be
considered during post-stretching operations including, but not
limited to, the material composition, the relaxation tendency of
the material, and the desired amount of percent recovery for a
particular application.
[0066] Relaxation Tendency
[0067] In most cases, the shape deformation material will possess a
tendency to return to its original, pre-stretched configuration.
This property may be described as a relaxation tendency. Although
the relaxation tendency may vary from material to material,
generally, the amount of relaxation tendency increases as the
elasticity of the material increases. Further, the amount of
relaxation tendency increases for a given material as the
temperature of the material increases.
[0068] Tension
[0069] During post-stretching operations, the stretched material
may be held under tension in a stretched state, gradually released
from a stretched state over time, or treated in some manner while
in a tensionless state. Typically, recoverable shape deformation or
percent recovery is larger when the shape deformation material is
held in a stretched state for a longer period of time. When the
shape deformation material is a polymeric fiber or film, the shape
deformation material is desirably held in a stretched state for at
least about 30 seconds. More desirably, the shape deformation
material is held in a stretched state for at least about ten
minutes. Even more desirably, the shape deformation material is
held in a stretched state for at least about one hour, and most
desirably, about 24 hours. The time under tension depends on a
molecular structure of the shape deformation polymer. For
poly(ether amide) shape deformation elastomer, e.g. PEBAX.RTM.
elastomer, the material can be held under tension for a very short
period of time. For polyester aromatic and aliphatic polyurethanes
with shape deformation, e.g. MORTHANE.RTM. polyurethanes, a longer
time under tension is preferred. The use of tension, especially in
combination with temperature, may be useful to preserve orientation
in the shape deformation material and protect the resulting
structure against undesirable shrinkage after stretching.
[0070] Temperature
[0071] The stretched shape deformation material may be subjected to
post-stretching operations at room temperature or at elevated
temperatures. The "setting" process (i.e., the process of
locking-in a desired amount of stretch) may be conducted in
accordance with a selected, predetermined temperature-time profile,
which is dependent on the structure of the shape deformation
material and the relaxation tendency of the shape deformation
material. In general, the setting process is conducted at
temperatures below the melting temperature of the shape deformation
material. Desirably, the setting process is conducted at
temperatures above the temperature of secondary relaxation
processes and temperatures above the glass transition temperature
of the soft segments in segmented block elastomers. This allows the
sturcture to relax during the setting process and reduce relaxation
tendency, which can result in increased shape deformation.
[0072] It is important to note that initial material temperature
may be important to provide the most efficient coupling of EMR
energy with the molecular structure of the material. Cooling down
the shape deformation material or preheating it before EMR
treatment, which depends on the specific molecular arrangement and
composition of a material, can shift the molecular-dipole
relaxation times in the frequency range of the EMR application
system, which typically operates in a frequency range of about
10.sup.9 Hz. This cooling or preheating can significantly enhance a
coupling of the EMR energy with the molecular structure of the
shape deformation material and can increase the activation
efficiency of the EMR energy. In addition to dipole relaxation, or
in place of dipole relaxation, ionic conductivity or ionic mobility
can be utilized for activation by EMR energy.
[0073] Other Post-Stretching Operations
[0074] Other additional post-stretching processes or operations,
such as UV treatment, ultrasonic treatment, high energy treatment,
or combinations of these treatments, may be incorporated into the
post-stretching process to modify the morphological state of the
stretched material and to maximize the percent recovery of the
shape deformation material upon activation.
[0075] The Activation Process
[0076] The present invention is further directed to a method of
causing the efficient recovery of at least a portion of the latent,
locked-in shape deformation of the above-described shape
deformation materials. The method comprises subjecting the shape
deformation material to an amount of activation energy in order to
effect a substantial change (i.e., recovery) in at least one
spatial dimension of the material. The method may be used to cause
the shape deformation of the above-described shape deformation
material itself or a product containing as one or more components
the above-described shape deformation material.
[0077] Recovery of latent, locked-in shape deformation of the shape
deformation material of the present invention is accomplished by
exposing the shape deformation material to an amount of activation
energy having a desired frequency and power level. Desirably, the
activation energy comprises electromagnetic radiation (EMR) having
a frequency range of from about 10 MHz to about 30 GHz. More
desirably, the activation energy comprises electromagnetic
radiation (EMR) having a frequency range of from about 20 MHz to
about 2500 MHz.
[0078] The shape deformation material of the present invention may
be exposed to a sufficient amount of activation energy to effect a
change in at least one spatial dimension of the material.
Desirably, the shape deformation material exhibits a desired amount
of percent recovery upon exposure to electromagnetic radiation
(EMR) for less than about three seconds. More desirably, the shape
deformation material exhibits a desired amount of percent recovery
upon exposure to electromagnetic radiation (EMR) for less than
about one second. Even more desirably, the shape deformation
material exhibits a desired amount of percent recovery upon
exposure to electromagnetic radiation (EMR) for less than about 0.5
seconds. Even more desirably, the shape deformation material
exhibits a desired amount of percent recovery upon exposure to
electromagnetic radiation (EMR) for less than about 0.05
seconds.
[0079] As shown by example in FIG. 4, an optimum percent recovery
range may be determined for a given shape deformation material and
a given activation energy unit. The combined effects of a power
level of a given activation energy unit and the speed of the shape
deformation material through the activation energy unit lead to a
variety of results including inefficient recovery of a sample,
melting of the sample, and desired recovery of the sample. As shown
in FIG. 4, when the speed is low (i.e., the residence time is
long), the sample absorbs too much energy and melts as it passes
through the unit. If the speed is too high and the power too low,
the residence time is too short and the sample cannot absorb enough
energy to be activated. Optimization occurs within the diagonal
region on FIG. 4 from about medium speed/medium power to high
speed/high power. Because this diagonal region appears to be
linear, it is believed that for at least some shape deformable
materials high recoveries at high web speeds is only limited by the
microwave power available and the ability of the shape deformable
material to absorb microwave energy at a high rate. The shape
deformable material can be designed to allow a high rate of EMR
absorption.
[0080] Percent recovery may vary depending on a number of factors
including, but not limited to, the shape deformation material; the
amount of latent, locked-in shape deformation; the pre-activation
treatments used to prepare the shape deformation material; and the
desired amount of percent recovery for a particular application.
For most applications, the percent recovery (%R) is desirably
greater than about 30% upon exposure to EMR energy for less than
about one second. For most applications, the percent recovery (%R)
is more desirably greater than about 60% upon exposure to EMR
energy for less than about one second. A preferred range of the
percent recovery is from about 15% to about 75% upon exposure to
EMR energy for less than about one second.
[0081] As discussed above, the use of EMR energy in the present
invention to activate shape deformation materials is advantageous
over conventional methods, which use thermal energy, for a number
of reasons. The use of EMR energy enables rapid molecular
reorientation (i.e., recovery) of a shape deformable material
having a latent, locked-in amount of shape deformation without a
substantial increase in the temperature of the shape deformable
material. As used herein, "a substantial increase in the
temperature of the shape deformable material" refers to an increase
in temperature of greater than about 15.degree. C. Desirably, the
shape deformable material exhibits a desired percent recovery while
experiencing a temperature change of less than about 12.degree. C.
More desirably, the shape deformable material exhibits a desired
percent recovery while experiencing a temperature change of less
than about 10.degree. C. Even more desirably, the shape deformable
material exhibits a desired percent recovery while experiencing a
temperature change of less than about 8.degree. C. Even more
desirably, the shape deformable material exhibits a desired percent
recovery while experiencing a temperature change of less than about
5.degree. C.
[0082] As opposed to conventional recovery methods, which desire
thermal heating of a shape deformable material, the activation
process of the present invention desirably minimizes the degree of
heating of the shape deformable material. Further, the activation
process of the present invention results in no surface overheating
of the shape deformation material, controlled energy delivery,
short exposure times, increased throughput, reduced material
degradation, and energy savings. Additionally, activation with EMR
energy advantageously occurs in a fraction of the time required for
hot air or convection oven activation using heat. Such conventional
processes require from as few as about 10 seconds to as great as
about 15 to 20 minutes for activation depending upon the particular
article or configuration. These processes require such relatively
long activation times because of the need to transfer heat from the
surface of the article to the interior of the article and because
the heat conductivity of the article, and dry air surrounding the
article, is poor. In contrast to the activation times of
conventional processes, the activation period in the present
invention may be lower than 0.01 seconds.
[0083] In some conventional processes, the recovery of shape
deformation is achieved by heating a shape deformable material to
temperatures below the melting temperature of the stretched polymer
material and above the stretching temperature. Low recovery
temperatures may result in low recoverable deformation, while
excessively high temperatures may result in melting of the
shape-deformed material. However, in the present invention using
EMR radiation, the temperature of the environment is not critical.
The temperature of the environment surrounding the shape deformable
material of the present invention may vary depending on the desired
conditions in a given room. For example, the activation process of
the present invention may be performed at room temperature or in a
cooled or heated zone.
[0084] The EMR treatment used in the present invention may be
provided, for example, by multi-mode, traveling wave, or single
mode resonating cavity applicators. A suitable microwave generator
and cavity is described in U.S. Pat. No. 5,536,921 to Hedrick et
al. and U.S. Pat. No. 5,916,203 to Brandon et al., which are hereby
incorporated by reference. Such a generator typically provides a
plurality of microwave standing waves within an enclosure or
cavity. The web of material can then be passed through the standing
waves where the incident microwave energy can be utilized within
the web. Microwave energy may then be supplied, continuously or
intermittently, to the continuously moving web of microwave
sensitive material at a rate, which activates the selected regions
on the web. The rate at which the energy is supplied is dependent
upon the type of material and the speed at which the composite
material is moving. A generator may also be configured to provide a
variable amount of microwave energy relative to the speed of the
web such that the energy provided increases as the web speed
increases. To provide such high levels of energy in such a short
time period, it may be desirable to have more than one microwave
cavity through which the web passes. For example, in one
embodiment, the system used in the present invention may include
from two to twenty cavities through which the web passes to provide
the necessary energy to activate the selected regions on the web of
material.
[0085] Alternatively, the EMR may be applied using a radio
frequency (RF) generator which would provide a uniform distribution
of activation energy through the shape deformation material. A
suitable RF system is described in U.S. Pat. No. 4,675,139 to Kehe
et al., which is incorporated herein by reference. Another suitable
RF system is described in U.S. Pat. No. 5,950,325, which is also
incorporated herein by reference. In this type of system, the
material is passed between two metal plates or electrodes. A
generator applies to the plates a high-frequency current of 1 to
200 megahertz that sets up an electric field in and around the
material. The web of material can then be passed through this field
where the incident RF energy can be utilized by the web.
[0086] The energy input in a RF activation system may be precisely
controlled since the voltage across the capacitor plates and the
gap between the plates are adjustable for optimum energy input.
Further, the process can be arranged in such a way that the
capacitor plates and/or plate electrodes provide energy into the
system, as well as, provide compaction or molding pressure on the
shape deformation material. In other words, the capacitor plates
and/or plate electrodes may be used to press the shape deformation
material to a desired thickness or shape while supplying activation
energy to the shape deformation material. In a further embodiment,
the capacitor plates and/or plate electrodes may be in the form of
pressure rolls, which can provide activation energy, compaction,
and transport of the activated product resulting in enhanced
processing speeds and a reduction in processing costs.
[0087] In one embodiment of the present invention, the desired EMR
application system is a National GEN6KWCONTROLA remote control unit
coupled to a Spellman MG1 0 series switch-mode power supply. These
units power a 2450 MHz microwave generator from Richardson
Electronics. The microwaves can be passed through a directional
coupler, waveguide, and stub tuner to a single mode resonating
cavity. Forward and reflected power in the system may be adjusted
and optimized for various materials through adjustments to the
generator control and stub tuner.
[0088] The activation process of the present invention may be
performed in a batch or continuous operation. Desirably, the
activation process is a continuous process, such as the process
shown in FIG. 1, wherein a composite material 10 is subjected to
EMR. The composite material 10 comprises a web of material 12
having numerous shape deformation materials 14 thereon. The
composite material 10 passes through EMR wave cavity 18 to activate
shape deformation material 14 and covert shape deformation material
14 into recovered material 16. Generator 60 supplies EMR energy
having a desired frequency range and power level. The speed of
composite 10 determines the exposure time of shape deformation
material 14.
[0089] The activation process of the present invention may be
performed using one or more of the above-mentioned EMR-generating
apparatus in a continuous operation. For example, one or more
microwave generators may be used in combination with one or more
radio wave generators. Further, one or more microwave generators
and/or one or more radio wave generators may be used in combination
with one or more conventional apparatus such as infrared,
ultraviolet, electron beam, or heated air activation systems.
[0090] Compared to conventional systems, which have used heated air
or heated rolls to activate webs or individual pieces of latent
elastic material, the use of EMR energy is less expensive, easier
to control, and faster to provide improved manufacturing efficiency
and quality. For example, in a manufacturing process for absorbent
articles such as diapers, the entire diaper article may be
manufactured and packaged while the shape deformation material of
the absorbent article is in a latent state. Prior to shipping the
articles, the shape deformation material within the absorbent
article may be activated by EMR energy as shown in FIG. 1.
[0091] Articles of Manufacture
[0092] The present invention is further directed to articles of
manufacture, which contain the above-described shape deformable
materials. The shape deformable material may represent a
substantial part of the article of manufacture or may represent one
of many components of the article. Further, the shape deformable
material may be used as a single layer component or may be present
as one layer of a multi-layer laminate within the article of
manufacture. Suitable articles of manufacture include, but are not
limited to, products containing an elastic portion, such as
diapers, as well as, products having a shrinkable, gatherable or
expandable component.
[0093] In one embodiment of the present invention, the shape
deformable material is in the form of a film, which is laminated to
one or more additional layers to form a composite article. The
additional layers may comprise additional films, nonwoven webs,
woven fabrics, foams, or a combination thereof. The resulting
laminated article is suitable for use in a number of applications,
such as disposable absorbent products. Such products include, but
are not limited to, absorbent personal care items such as diapers,
training pants, adult incontinence products, feminine care products
such as sanitary napkins and tampons, and health care products such
as wound dressings. Other products include surgical drapes,
surgical gowns, and other disposable garments.
[0094] The composite material of this embodiment is
representatively illustrated in FIG. 2. As can be seen in FIG. 2,
the composite material 20 comprises a nonwoven web layer 22; and
strips of shape deformable material 24 and 26, which are attached
to layer 22. The strips of shape deformable material 24 and 26 may
be attached to nonwoven web layer 22 by any means known to those of
ordinary skill in the art. Depending on the amount and degree of
latent, locked-in shape deformation within the strips of shape
deformable material 24 and 26, activation of the composite material
results in a desired gathered composite material.
[0095] One article of manufacture of particular interest is an
absorbent garment article representatively illustrated in FIG. 3.
As can be seen in FIG. 3, the absorbent garment may comprise a
disposable diaper 30, which includes the following components: a
front waist section 31; a rear waist section 32; an intermediate
section 33, which interconnects the front and rear waist sections;
a pair of laterally opposed side edges 34; and a pair of
longitudinally opposed end edges 35. The front and rear waist
sections include the general portions of the article, which are
constructed to extend substantially over the wearers front and rear
abdominal regions, respectively, during use. The intermediate
section 33 of the article includes the general portion of the
article, which is constructed to extend through the wearer's crotch
region between the legs. The opposed side edges 34 define leg
openings for the diaper and generally are curvilinear or contoured
to more closely fit the legs of the wearer. The opposed end edges
35 define a waist opening for the diaper 30 and typically are
straight but may also be curvilinear.
[0096] FIG. 3 is a representative plan view of a diaper 30 of the
present invention in a flat, uncontracted state. Portions of the
structure are partially cut away to more clearly show the interior
construction of the diaper 30, and the surface of the diaper which
contacts the wearer is facing the viewer. The diaper 30 further
includes a substantially liquid impermeable outer cover 36; a
porous, liquid permeable bodyside liner 37 positioned in facing
relation with the outer cover 36; an absorbent body 38, such as an
absorbent pad, which is located between the outer cover and the
bodyside liner; and fasteners 42. Marginal portions of the diaper
30, such as marginal sections of the outer cover 36, may extend
past the terminal edges of the absorbent body 38. In the
illustrated embodiment, for example, the outer cover 36 extends
outwardly beyond the terminal marginal edges of the absorbent body
38 to form side margins 40 and end margins 41 of the diaper 30. The
bodyside liner 37 is generally coextensive with the outer cover 36,
but may optionally cover an area, which is larger or smaller than
the area of the outer cover 36, as desired.
[0097] Shape deformable material as described above may be
incorporated into various parts of the diaper 30 illustrated in
FIG. 3. Desirably, a pair of laterally opposed side strips 44
and/or a pair of longitudinally opposed end strips 46 comprise the
shape deformable material of the present invention. Upon
activation, strips 44 and 46 form gathered portions, which provide
a snug fit around the waist and leg openings of the diaper 30.
[0098] Optimizing Interaction of Polymer With EMR Energy The
present invention is also directed to a method of making shape
deformable polymers in an effort to optimize the interaction of the
shape deformable polymer with a selected activation energy. By
incorporating one or more selected moieties into the polymer
backbone and/or positioning one or more selected moieties at
strategic sites along the polymer backbone of the shape deformable
polymer, one can tailor a specific shape deformable polymer, which
will optimally respond to a selected activation energy, such as
electromagnetic energy (EMR) having a specific wavelength.
[0099] For shape deformable polymers, the efficiency of EMR
absorption is related to the dielectric properties of the polymer.
Typically, a shape deformable polymer suitable for use in the
present invention demonstrates a high dielectric loss factor in a
frequency range corresponding to the EMR energy. Desirably, the
shape deformable polymer has a dielectric loss factor at a given
frequency within the EMR frequency range of from about 10 MHz to
about 30 GHz of greater than about 0.05. More desirably, the shape
deformable polymer has a dielectric loss factor at a given
frequency within the EMR frequency range of from about 10 MHz to
about 30 GHz of greater than about 0.1. Even more desirably, the
shape deformable polymer has a dielectric loss factor at a given
frequency within the EMR frequency range of from about 10 MHz to
about 30 GHz of greater than about 0.20. Even more desirably the
shape deformable polymer has a dielectric loss factor at a given
frequency within EMR frequency range of from about 10 MHz to about
30 GHz of greater than about 0.25.
[0100] By increasing the dielectric loss factor of a synthesized
shape deformable polymer, one can increase the responsiveness of
the polymer to electromagnetic energy having a specific wavelength.
As discussed above with regard to functional groups within a shape
deformable polymer, specifically selected moieties along the
polymer chain and the positioning of moieties along the polymer
chain can effect the dielectric loss factor of the shape deformable
polymer, and enhance the responsiveness of the polymer to
electromagnetic energy. Desirably, the presence of one or more
moieties along the polymer chain causes one or more of the
following: (1) an increase in the dipole moments of the polymer;
and (2) an increase in the unbalanced charges of the polymer
molecular structure. Suitable moieties include, but not limited to,
aldehyde, ester, carboxylic acid, sulfonamide and thiocyanate
groups.
[0101] The selected moieties may be covalently bonded or ionically
attached to the polymer chain. As discussed above, moieties
containing functional groups having high dipole moments are desired
along the polymer chain. Suitable moieties include, but are not
limited to, urea, sulfone, amide, nitro, nitrile, isocyanate, and
ketone groups. Other suitable moieties include moieties containing
ionic groups including, but are not limited to, sodium, zinc, and
potassium ions.
[0102] One example of modifying a polymer chain to enhance the
responsiveness of the polymer chain is shown below: 1
[0103] In the above example, a nitro group is attached to the aryl
group within the polymer chain. It should be noted that the nitro
group may be attached at the meta or para position of the aryl
group. Further, it should be noted that other groups may be
attached at the meta or para position of the aryl group, as shown
above, in place of the nitro group. Suitable groups include, but
are not limited to, nitrile groups. In addition to the modification
shown above, one could incorporate other monomer units into the
polymer above to further enhance the responsiveness of the
resulting polymer. For example, monomer units containing urea
and/or amide groups may be incorporated into the above polymer.
[0104] A further example of designing a shape deformable polymer is
given below, wherein one or more moieties, X and Y, are bonded to
specific sites along a block copolymer chain: 2
[0105] X and Y may be bonded on soft blocks, hard blocks, or both
soft and hard blocks, as well as, on the ends of the polymer chain.
X and Y may be randomly bonded or uniformly bonded along the
polymer chain. Suitable moieties include aldehyde, ester,
carboxylic acid, sulfonamide and thiocyanate groups. However, other
groups having or enhancing unbalanced charges in a molecular
structure can also be useful; or a moiety having an ionic or
conductive group such as, e.g., sodium, zinc, and potassium ions.
However, other ionic or conductive groups can also be used.
[0106] It should be noted that moieties X and Y may also be bonded
to the same soft or hard block within a given polymer chain. In one
embodiment shown below, X and Y are bonded to the same soft or hard
block within a given polymer, wherein X is a moiety having a
positive charge and Y is a moiety having a negative charge: 3
[0107] In such a configuration, the unbalanced charge within one
polymer segment results in enhanced interaction between the polymer
and electromagnetic radiation.
[0108] A further method of optimizing the interaction of a given
polymer and an electromagnetic field is to identify a maximum
dielectric loss factor of the polymer along the frequency range of
the electromagnetic field. By identifying a maximum dielectric loss
factor value of a shape deformable polymer at a specific frequency
within the EMR frequency range of from about 10 MHz to about 30
GHz, one can subject the shape deformable polymer to an activation
energy at the specific frequency corresponding to the maximum
dielectric loss factor of the polymer.
[0109] Other factors may be considered when optimizing process
conditions during a recovery process. For example, the dielectric
loss factor of a shape deformable polymer may be significantly
influenced by the temperature of the polymer. For illustrative
purposes only, FIGS. 5 and 6 graphically display the change in
value of the dielectric loss factor of two polymers versus
frequency at selected temperatures. FIG. 5 graphically displays the
change in value of the dielectric loss factor of polyether amide
copolymer, PEBAX.RTM. 2533 film, stretched 6.times., versus
frequency at temperatures of 0.degree. C., 25.degree. C.,
45.degree. C., and 75.degree. C. FIG. 6 graphically displays the
change in value of the dielectric loss factor of polyurethane,
MORTHANE.RTM. PS370-200 film, stretched 6.times., versus frequency
at temperatures of 0.degree. C., 25.degree. C., 45.degree. C., and
75.degree. C. The stretched PEBAX.RTM. 2533 film demonstrated a
dramatic increase in dielectric loss factor at a temperature of
75.degree. C. in a frequency range from about 0.25 GHz to about 2.5
GHz with a maximum loss factor of about 5 at about 1 GHz as
illustrated in FIG. 5. The stretched MORTHANE.RTM. PS370-200 film
demonstrated a dramatic increase in a dielectric loss factor at a
temperature of 75.degree. C. in a frequency range from about 0.5
GHz to about 2.4 GHz with a maximum loss factor of about 1.25 at
about 1 GHz as illustrated in FIG. 6. These data show that shape
deformation materials can exhibit a significant dependence of a
dielectric loss factor upon frequency of EMR and a preheating of
the material. This finding can provide an insight into a better
design of a microwave application system in terms of preferred
frequency range and preconditioning of the shape deformation
materials.
[0110] As discussed above, EMR absorbers may be combined with a
specifically designed shape deformable polymer to further enhance
the interaction of the polymer with electromagnetic radiation.
[0111] The present invention is further described by the examples
which follow. Such examples, however, are not to be construed as
limiting in any way either the spirit or scope of the present
invention. In the examples, all parts are parts by weight unless
stated otherwise.
EXAMPLES
[0112] The following examples were conducted to produce shape
deformation materials having an amount of locked-in shape
deformation, and to activate the materials. Degree of
stretch/stretch ratio, stretch rate, and stretch hold/cooling rate
were some of the factors considered in order to introduce the most
latent, lock-in shape deformation.
[0113] Materials
[0114] Two types of polyester-based aromatic thermoplastic
polyurethanes and one type of polyester aliphatic polyurethane were
tested, all supplied by Morton International (Chicago, Ill.). The
first polyurethane, MORTHANE.RTM. PS370-200 (melt index MI=5, shore
hardness 78, 100% tensile modulus 3.4 MPa (500 psi)) was chosen for
its good elastic properties, its low modulus, high strength and its
soft feel. The second polyurethane, MORTHANE.RTM. PS79-200 (melt
index MI=20, shore hardness 85, 100% tensile modulus 5.9 MPa (850
psi)) was chosen for its good processability and reduced tackiness.
The third polyurethane, which was the polyester aliphatic
polyurethane, was MORTHANE.RTM. PN3429-219 (melt index MI=50) and
was selected for its good processability. Each polyurethane was
obtained in pellet form and extruded into films using a Haake
twin-screw extruder. Before extruding into a film, the resin was
dried at 80.degree. C. for MORTHANE.RTM. PS370-200, at 60.degree.
C. for MORTHANE.RTM. PS79-200 and 50.degree. C. for MORTHANE.RTM.
PN3429-219. The extruded films had a thickness of approximately 2
mil.
[0115] Test Procedures
[0116] The following test procedures were used to determine
properties of the films.
[0117] Dielectric Properties
[0118] Dielectric measurements were made using a Network Analyzer
capable of generating a low power (0 to +5 dBm) swept Radio
Frequency (RF) signal over a frequency range of 300 kHz to 3 GHz.
Samples of single fold (i.e. two layer) thickness are placed in
contact with a coaxial probe yielding low-loss resolution
measurements for solid films. Specifically, an HP 8752C (300 kHz to
3 GHz) RF Network Analyzer, and an HP 85070B Reflectance Dielectric
Probe are used for the dielectric determinations. Once calibrated,
the instrument is used to directly measure dielectric constant
(e'), and dielectric loss factor (e"). From this information,
calculations can be made for power dissipation factor (loss
tangent, e"/e'). All calculations and graphical presentations were
performed using MatLab (Matrix Laboratory) software from The
Mathworks, Natick, Mass. The various temperature measurements were
made by placing the film on a ceramic block maintained at the
appropriate temperature during measurement.
[0119] The dielectric data (e', e" and e"/e') for four different
samples are provided below. Sample 1 is polyester aliphatic
polyurethane, PN3429-219. Sample 2 is polyester aromatic
polyurethane, PS370-200. Sample 3 is PEBAX.RTM. polyether amide
copolymer 2533-film stretched 6.times. at room temperature. Sample
4 is polyurethane, PS370-200 film stretched 6.times. at 80.degree.
C.
1 MHz e' e'' e''/e' Sample 1 0.degree. C. 27.1 1.21 0.12 0.099174
915 1.799457 0.08806 0.048937 2450 1.761119 0.087892 0.049907
25.degree. C. 27.1 2.76 0.604 0.218841 915 2.346763 0.147718
0.062945 2450 2.233475 0.137417 0.061526 45.degree. C. 27.1 2.14
0.15 0.070093 915 2.00048 0.10122 0.050598 2450 1.905912 0.115385
0.060541 75.degree. C. 27.1 3.72 0.241 0.064785 915 2.952051
0.260132 0.088119 2450 2.714274 0.266041 0.098016 Sample 2
0.degree. C. 27.1 1.14 0.441 0.386842 915 1.723 0.077036 0.04471
2450 1.674601 0.096932 0.057884 25.degree. C. 27.1 3.39 0.277
0.081711 915 2.963203 0.219667 0.074132 2450 2.794656 0.252468
0.09034 45.degree. C. 27.1 2.56 0.11 0.042969 915 2.137411 0.123166
0.057624 2450 2.020432 0.131741 0.065204 75.degree. C. 27.1 2.51
0.13 0.051793 915 1.884419 0.131057 0.069548 2450 1.79201 0.113719
0.063459 Sample 3 0.degree. C. 27.1 2.32 0.31 0.133621 915 2.181792
0.13449 0.061642 2450 2.101588 0.137296 0.06533 25.degree. C. 27.1
3.48 0.14 0.04023 915 2.86928 0.153418 0.053469 2450 2.749838
0.20396 0.074172 45.degree. C. 27.1 2.28 0.19 0.083333 915 2.218893
0.190131 0.085687 2450 2.094158 0.173597 0.082896 75.degree. C.
27.1 2.9 1.1 0.37931 915 2.279023 5.011064 2.198777 2450 2.063194
0.800902 0.388186 Sample 4 0.degree. C. 27.1 1.4 0.385 0.275 915 1
779433 0.09235 0.051899 2450 1.710493 0.095685 0.05594 25.degree.
C. 27.1 4.27 0.56 0.131148 915 3.544206 0.293757 0.082884 2450
3.351744 0.310472 0.09263 45.degree. C. 27.1 3.34 0.19 0.056886 915
2.435807 0.182267 0.074828 2450 2.295267 0.176522 0.076907
75.degree. C. 27.1 2.79 0.48 0.172043 915 3.440623 0.914258
0.265725 2450 2.410955 0.394036 0.163436
[0120] As can be seen from the data, the high dielectric losses of
the materials over the broad range of frequencies shows that the
materials may be activated by EMR in the RF and/or microwave
frequency ranges. For example, each of the samples had a higher
dielectric loss as measured at 25.degree. C. and 27.1 MHz than as
measured at 25.degree. C. and 2450 MHz. Additionally, the higher
dielectric loss factor at 27.1 MHz suggests that these materials
will be more responsive to EMR in the RF range than in the
microwave range.
[0121] Stretching Procedures to Impart Latent Deformation
[0122] An MTS Sintech 1/D instrument equipped with a 50-pound load
cell and an environmental chamber was used to stretch the samples
to impart a desired amount of shape deformation. Samples of each
film were cut 1" wide by 3" to 4" long and were labeled and marked
in black ink with lines 20 mm apart. Samples were then placed in
the grips of the MTS Sintech 1/D instrument spaced 2" apart and
stretched a desired amount. Samples were stretched from 3.times.
(i.e., three times the original length) to more than 6.times., at a
desired stretch rate. Stretch rates were either 100 mm/min (i.e.,
the "slow" rate) or 500 mm/min (i.e., the "fast" rate). When
necessary, the grips and sample were placed in the environmental
chamber and heated to a desired temperature, which varied from
about 37.degree. C. to about 100.degree. C., allowed to
equilibrate, and then stretched the desired amount at the desired
rate.
[0123] Unless otherwise noted, after stretching, the sample was
held stretched at the stretching temperature for 1 minute. Then,
the sample was cooled by one of two methods. "Slow cooling" was one
method wherein the environmental chamber door was opened and the
stretched sample exposed to a fan until the sample had reached room
temperature at which point the sample was released from the
stretched position and removed. The other method was "quenching,"
wherein the environmental chamber door was opened and the sample
was sprayed with a cooling agent (i.e., Blow-Off freeze spray
comprising 1,1,1,2-tetrafluoroethane) for a number of passes while
the sample was released from the stretched position and removed
from the chamber.
[0124] The distance between the lines was measured and recorded and
new lines were marked in red 20 mm or 40 mm apart depending upon
the sample length. Latent, locked-in shape deformation, or percent
latency, was defined as the change in length from the stretched
sample to the initial sample, divided by the initial sample length,
and multiplied by 100.
[0125] Procedure For Measuring Temperature During Activation
[0126] The temperature of sample films exposed to microwave
radiation was determined as follows. An infrared imaging camera
having the following specifications was used to detect the surface
temperature of the sample films:
2 Camera: Agema ThermaCam PM595 Detector: microbolometer, 7.5-13
.mu.m response Accuracy: +/- 2.degree. C., +/- 2% Range:
-40.degree. C. to 1500.degree. C. Field of View (FOV): 24.degree.
.times. 18.degree. Minimum Focus 0.5 m Distance (FD.sub.min): Array
Size: 320 .times. 240 pixels
[0127] The camera was set up on the microwave unit at a location
about 7 inches from the exit of the microwave application cavity
and about 18 inches above the film sample.
[0128] Rectangular strips of film were placed on a polypropylene
web having a very low absorption of microwaves. The used
polypropylene web was PP nonwoven with dielectric properties
measured at room temperature of 25.degree. C. and frequency of 2450
MHz being: e'=1.37 and e"=0.0166. The dielectric loss factor, e",
was about one order of magnitude (10 times) lower compared to
activatable, microwave responsive shape deformation materials. Low
loss factor for PP nonwoven web suggests a very low absorption of
microwaves. To ensure that the temperatures measured by the camera
were accurate, film samples were run through the microwave cavity
without exposure to microwave radiation. The film samples were
found to have an average temperature of 25.5.degree. C., within
2.degree. C. of room temperature.
[0129] Film samples were then run through the microwave cavity at a
variety of speeds and power levels. Images of the film samples were
taken and stored on flash memory cards as the film samples exited
the microwave cavity. Using the camera's temperature analysis
software, temperature information was collected for each
sample.
EXAMPLE 1
Effect of Stretch Rate on the Amount of Locked-in Shape
Deformation
[0130] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using a slow stretch rate and a fast stretch rate. The
strips were stretched up to 6 times their initial length at three
separate temperatures, 25.degree. C., 50.degree. C., and 70.degree.
C. using a Sintech tensile tester (SINTECH 1/D) and an
environmental chamber.
[0131] The results of the tests are given below in Table 1.
3TABLE 1 Stretch Rate Results Temperature 25.degree. C. 50.degree.
C. 70.degree. C. Stretch Rate Slow Fast Slow Fast Slow Fast %
Latency 15 20 75 75 145 150
[0132] As can be seen in Table 1, the stretch rate did not
significantly effect the percent latency of MORTHANE.RTM. PS
370-200. However, the temperature had a significantly effect on the
percent latency of MORTHANE.RTM. PS 370-200.
EXAMPLE 2
Effect of Draw Ratio on the Amount of Locked-in Shape
Deformation
[0133] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using three different draw ratios: 4.times., 5.times.,
and 6.times.. The strips were stretched at three separate
temperatures, 25.degree. C., 50.degree. C., and 70.degree. C. using
a Sintech tensile tester (SINTECH 1/D) and an environmental
chamber.
[0134] The results of the tests are given below in Table 2.
4TABLE 2 Draw Ratio Results Temperature 25.degree. C. 50.degree. C.
70.degree. C. Draw Ratio 4x 5x 6x 4x 5x 6x 4x 5x 6x % Latency 15 15
25 80 120 75 125 -- 150
[0135] As can be seen in Table 2, the draw ratio did not
significantly effect the percent latency of MORTHANE.RTM. PS
370-200.
EXAMPLE 3
Effect of Stretch Temperature on the Amount of Locked-in Shape
Deformation
[0136] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using three different temperatures: 25.degree. C.,
50.degree. C., and 70.degree. C. The strips were stretched at two
different draw ratios, 4.times. and 6.times., using a Sintech
tensile tester (SINTECH 1/D) and an environmental chamber.
[0137] The results of the tests are given below in Table 3.
5TABLE 3 Temperature Results Temperature 25.degree. C. 50.degree.
C. 70.degree. C. Draw Ratio 4x 6x 4x 6x 4x 6x % Lateney 15 25 80 --
125 150
[0138] As can be seen in Table 3, the stretch temperature had a
significantly effect on the percent latency of MORTHANE.RTM. PS
370-200.
EXAMPLE 4
Effect of Stretch Hold and Cooling Rate on the Amount of Locked-In
Shape Deformation
[0139] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched at different temperatures: 70.degree. C. and 90.degree.
C. The strips were stretched at a draw ratio of 6.times., using a
Sintech tensile tester (SINTECH 1/D) and an environmental chamber.
The samples were either slowly cooled or quenched as described
above. The samples were allowed to cool or quenched after being
held in a stretched position for one minute, and also without being
held.
[0140] The results of the tests are given below in Table 4.
6TABLE 4 Stretch Hold/Cooling Rate Results Temperature 70.degree.
C. 90.degree. C. Stretch Hold Load No Load Load No Load Cooling SC
Q SC Q SC Q SC Q Method % Latency 145 145 140 150 235 180 210
190
[0141] As can be seen in Table 4, the MORTHANE.RTM. PS 370-200
samples had a larger amount of percent latency when slowly cooled
after being held for one minute at a given stretch temperature and
then allowed to cool as opposed to the samples allowed to cool
without being held. Quenching reduced the amount of time the
samples were held and allowed to relax. Consequently, these samples
generally had less percent latency. However, conclusions regarding
the overall effect of quenching was hard to determine from the
above data.
[0142] The results of the MORTHANE.RTM. PS 370-200 samples at
90.degree. C. indicate that stretch holding and cooling rate has a
more significant effect on the percent latency than similar samples
tested at 70.degree. C. In these samples, slow cooling produced the
best results in percent latency.
EXAMPLE 5
Effect of Type of Microwave Generator on the Percent Recovery of
Locked-In Shape Deformation
[0143] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using a fast stretch rate and a draw ratio of 6.times..
The strips were stretched using a Sintech tensile tester (SINTECH
1/D) and an environmental chamber. The strips were then exposed to
microwaves from a diffuse microwave oven or an industrial microwave
unit. Both microwave generators operated at 2450 MHz and
approximately 900W. The diffuse microwave unit was a standard
household microwave oven manufactured by General Electric.
[0144] The results of the tests are given below in Table 5.
7TABLE 5 Type of Microwave Oven Results Type of Oven Diffuse
Industrial % Recovery Up to 45% 60%
[0145] As can be seen in Table 5, the type of microwave oven
effects the percent recovery of MORTHANE.RTM. PS 370-200. In the
diffuse household microwave oven, the multi-mode microwaves are
distributed throughout the cavity; however, in the industrial
microwave oven, the single-mode resonating cavity is providing more
efficient delivery and absorption of EMR by EMR responsive
material.
EXAMPLE 6
Determining Optimum Power and Speed of Industrial Microwave
Generator to Maximize the Percent Recovery of Locked-In Shape
Deformation
[0146] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using a fast stretch rate and a draw ratio of 6.times..
The strips were stretched using a Sintech tensile tester (SINTECH
1/D) and an environmental chamber. The strips were then exposed to
microwaves from the industrial microwave unit described in Example
5. The industrial microwave generator operated at 2450 MHz. The
power was adjusted from as low as approximately 220W to as much as
approximately 900W. The speed of the sample through the generator
was adjusted from as low as about 17.1 ft/min to as much as about
120 ft/min.
[0147] The results of the tests are shown in FIG. 4.
EXAMPLE 7
Activation of Sample Using EMR Energy
[0148] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched to 6 times their initial length at 70.degree. C. using a
Sintech tensile tester (SINTECH 1/D) and an environmental chamber.
The resulting latent (locked in) deformation was 135%. The
stretched film was placed on a polypropylene, nonwoven web running
at a speed of 68 ft/min.
[0149] The web and the film were run through an electromagnetic
radiation (EMR) application system operating at 900W. The EMR
application system consisted of a National GEN6KWCONTROLA remote
control unit coupled to a Spellman MG10 series switch-mode power
supply. These units powered a 2450 mHz microwave generator from
Richardson Electronics. The microwaves were passed through a
directional coupler, waveguide, and stub tuner to a single mode
resonating cavity. Forward and reflected power were adjusted and
optimized for various materials through adjustments to the
generator control and stub tuner.
[0150] The time of exposure to microwave irradiation was
approximately 0.3 seconds. The measured dimensional change of the
film in the machine direction (MD) after EMR treatment was 57%
based on the stretched film length.
COMPARATIVE EXAMPLE 1
[0151] Activation of Sample Using Thermal Energy
[0152] A MORTHANE.RTM. PU PS 370-200 film sample was stretched
using the procedure of Example 7. The stretched sample was placed
in a convection oven for 20 minutes at a temperature of 73.degree.
C. The sample was removed from the oven, and its dimensions were
measured. The dimensional change of the film in the MD after
thermal treatment was 25% based on the stretched film length.
EXAMPLE 8
Activation of Sample Using EMR Energy
[0153] Rectangular strips of MORTHANE.RTM. PU PS 370-200 were
stretched to 6 times their original length at 90.degree. C. using a
Sintech tensile tester (SINTECH 1/D) and an environmental chamber.
The resulting latent deformation was 220%. The stretched film was
placed on a polypropylene nonwoven web running at a speed of 68
ft/min.
[0154] The web and the film were run through an EMR application
system as in Example 7 operating at 880W. The time of exposure to
microwave irradiation was approximately 0.3 seconds. The measured
dimensional change of the film in MD after EMR treatment was 67%
based on the stretched film length.
COMPARATIVE EXAMPLE 2
Activation of Sample Using Thermal Energy
[0155] A MORTHANE.RTM. PU PS 370-200 film sample was stretched
using the same procedure as in Example 8. The measured latent
deformation was 165%. The stretched sample was placed in a
convection oven and held for 20 minutes at a temperature of
90.degree. C. The sample was removed, and its dimensions were
measured. The dimensional change of the film in the MD was 47%
based on the stretched film length.
EXAMPLE 9
Activation of Sample Using EMR Energy
[0156] Rectangular strips of MORTHANE.RTM. polyester based PU PS
79-200 were stretched to 6 times their original length at
25.degree. C. using a Sintech tensile tester. The resulting latent
deformation was 120%. The stretched film was placed on a
polypropylene nonwoven web running at a speed of 140 ft/min.
[0157] The web and the film were run through the EMR application
system of Example 7 operating at 860W. The time of exposure to
microwave irradiation was approximately 0.1 seconds. The measured
dimensional change of the film in MD after EMR treatment was 46%
based on the stretched film length.
EXAMPLE 10
Activation of Sample Using EMR Energy
[0158] A 90/10 blend of MORTHANE.RTM. PU PS 370-200 and
polyethylene oxide (PEO) was produced using a Haake laboratory twin
screw extruder. Rectangular strips of film made from the 90/10
blend of PU PS 370-200 and PEO were stretched to 6 times their
original length at 50.degree. C. using a Sintech tensile tester and
an environmental chamber. The resulting latent deformation was
180%. The stretched film was placed on a polypropylene nonwoven web
running at a speed of 140 ft/min.
[0159] The web and the film were run through the EMR application
system of Example 7 operating at 1250W. The time of exposure to
microwave radiation was approximately 0.1 seconds. The measured
dimensional change of the film in the MD after EMR treatment was
45% based on a stretched film length.
EXAMPLE 11
Activation of Sample Using EMR Energy
[0160] A multi-layer film of eight alternating layers of
MORTHANE.RTM. PU PS 370-200 and PEO resin was produced using a
microlayer coextrusion line available at Case Western Reserve
University (Cleveland, Ohio). The PEO resin POLYOX.RTM. WSR-N-3000
was supplied by Union Carbide Corporation in powder form and
pelletized at Planet Polymer Technologies (San Diego, Calif.).
Rectangular strips of the multi-layer PU PS 370-200/PEO (50/50)
film were stretched to 5 times their original length at 25.degree.
C. using a Sintech tensile tester. The resulting latent deformation
was 270%. The resulting film samples were placed on a polypropylene
nonwoven web running at a speed of 68 ft/min.
[0161] The web and the film were run through the EMR application
system of Example 7 operating at 900W. The time of exposure to
microwave radiation was approximately 0.3 seconds. The measured
dimensional change of the film in the MD after EMR treatment was
54% based on the stretched film length.
COMPARATIVE EXAMPLE 3
[0162] Activation of Sample Using Thermal Energy
[0163] The multi-layer PU PS 370-200/PEO (50/50) film of Example 11
was stretched to 6 times its original length at 25.degree. C. using
a Sintech tensile tester. The resulting latent deformation was
about 330%. The stretched sample was placed in a convection oven
for 20 minutes at a temperature of 73.degree. C. The sample was
removed from the oven, and its dimensions were measured. The
dimensional change of the film in the MD was 65% based on the
stretched film length.
COMPARATIVE EXAMPLE 4
Activation of Sample Using Thermal Energy
[0164] A 50/50 blend of PU PS 370-200 and polyethylene oxide (PEO)
was produced using a Haake laboratory twin screw extruder.
Rectangular strips of film, made from the 50/50 blend, were
stretched to 6 times their original length at 25.degree. C. The
resulting latent deformation was about 170%. The stretched sample
was placed in a convection oven for 20 minutes at a temperature of
65.degree. C. The sample was removed from the oven, and its
dimensions were measured. The dimensional change of the film in the
MD was 63% based on the stretched film length.
[0165] Examples 10, 11 and Comparative Examples 3 and 4 demonstrate
that blending or multi-layering/micro-layering of a shape
deformation elastomer with another non-elastomeric shape
deformation polymer can improve latent deformation properties,
especially at lower stretching temperatures, and can significantly
increase recoverable deformation as a result of activation by
thermal energy or EMR energy.
EXAMPLE 12
Effect of Activation Energy on the Temperature of a Shape
Deformable Material
[0166] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched using a slow stretch rate or a fast stretch rate. The
strips were stretched at a draw ratio of 6 times their initial
length at a temperatures of 80.degree. C. using a Sintech tensile
tester (SINTECH 1/D) and an environmental chamber.
[0167] The strips were exposed to microwave radiation from an
industrial microwave application system, which generated microwaves
at 2450 MHz at a power level of 1.5 kW with a reflected power of
1.0 kW. The speed of the film samples through the microwave
application system was about 59 ft/min., providing an exposure time
of about 0.3 seconds. The system was described in Example 7 in
further detail.
[0168] The average measured dimensional change of the film samples
in the machine direction after EMR treatment was about 50% based on
the stretched film length. The average temperature across the
surface of the film samples was after EMR treatment was about
36.7.degree. C. as measured by the above-described procedure.
COMPARATIVE EXAMPLE 5
Effect of Thermal Energy on the Temperature of a Shape Deformable
Material
[0169] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched as in Example 12. The strips were exposed to thermal
energy from a hot air oven. The film samples were placed in the
convection oven at 37.degree. C.
[0170] Two sets of film samples were placed in the oven. One set of
film samples were placed in the oven for 15 seconds, while the
second set of film samples were placed in the oven for 15 minutes.
The first set of film samples exhibited no substantial change in
the machine direction after exposure for 15 seconds. The second set
of film samples exhibited a change in the machine direction of
about 20% after exposure for 15 minutes.
[0171] The average measured dimensional change of the film samples
in the machine direction after EMR treatment was about 50% based on
the stretched film length. The average temperature across the
surface of the film samples was after EMR treatment was about
36.7.degree. C. as measured by the above-described procedure.
COMPARATIVE EXAMPLE 6
Effect of Thermal Energy at a Higher Temperature on the Temperature
of a Shape Deformable Material
[0172] Rectangular strips of MORTHANE.RTM. PS 370-200 were
stretched and thermally heated as in Comparative Example 5 except
that the oven temperature was set at 50.degree. C.
[0173] The first set of film samples exhibited a change in the
machine direction of about 17% after exposure for 15 seconds.
[0174] The second set of film samples exhibited a change in the
machine direction of about 30% after exposure for 15 minutes.
[0175] The average measured dimensional change of the film samples
in the machine direction after EMR treatment was about 50% based on
the stretched film length. The average temperature across the
surface of the film samples was after EMR treatment was about
36.7.degree. C. as measured by the above-described procedure.
[0176] As shown in Example 12 and Comparative Examples 5 and 6,
exposure to microwave radiation produced greater changes in the
machine direction of a stretched film than exposure to thermal
energy, even though the time of exposure was significantly less.
Further, microwave exposure did not result in a substantial change
in the temperature of the film samples, as opposed to the changes
observed in a convection oven.
EXAMPLE 13
Non-elastomeric shape deformable material
[0177] Rectangular strips of poly (butylenes succinate adipate)
copolymer, aliphatic polyester BIONOLLE.RTM. 3001 thermoplastic
resin obtained from Showa Highpolymer Co. Ltd. (Japan), were
stretched at 65.degree. C. using a tensile tester and environmental
chamber up to 5.times. of stretch ratio in the machine direction
(MD). The percent latent deformation was measured to be about 280%
based on the initial length of the film.
[0178] The stretched strips of BIONOLLE.RTM. 3001 were placed in a
convection oven for 20 minutes at a temperature of 750 C. After 20
minutes, the sample was removed from the oven, and its dimensions
were measured. The dimensional change (shrinkage) of the film in
the MD after thermal treatment was 35% based on the stretched film
length.
[0179] The stretched strips of BIONOLLE.RTM. 3001 with latent
deformation of about 280% in MD were exposed to EMR for about 45
seconds using a standard household microwave oven manufactured by
GE and operating at 2450 MHz and approximately 900W. After 45
seconds, the sample was removed from the microwave oven, and its
dimensions were measured. The dimensional change (shrinkage) of the
film in the MD after thermal treatment was 25% based on the
stretched film length.
[0180] The dielectric properties of the BIONOLLE.RTM. 3001 film
samples were measured at a temperature of 25.degree. C. and a
frequency of 2450 MHz. The dielectric constant, e', was 1.55 and
the dielectric loss factor, e", was 0.0502. The high dielectric
loss factor indicates that the BIONOLLE.RTM. 3001 comprises groups
with large dipole moments and can be responsive to EMR.
[0181] These examples demonstrate that non-elastomeric polymer can
possess a shape deformation property, which can be activated by
heat. Also, this shape deformation can be activated by using EMR,
when the non-elastomeric shape deformation material comprises
groups such as, e.g., ester groups, having large dipole moments and
providing sufficiently large dielectric loss factor.
[0182] While the specification has been described in detail with
respect to specific embodiments thereof, it will be appreciated
that those skilled in the art, upon attaining an understanding of
the foregoing, may readily conceive of alterations to, variations
of, and equivalents to these embodiments. Accordingly, the scope of
the present invention should be assessed as that of the appended
claims and any equivalents thereto.
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